I’ve had this happen twice now.
Set up a brand new FreePBX 15 system on a Vultr VM.
go through install, perform all updates through the webui
go to admin > system admin > network settings > change eth0 from DHCP to static
(Vultr support recommended this to keep the IP static)
system comes back online and you can’t connect. Use the vultr console to log in and the Eth0 is not up, bring it up and it now has an IPV6 address.
I’ve had this happen twice now in the last 3 days with two different fresh builds.
look into /etc/sysconfig/network-scripts/ifcfg-eth0 and the file is now empty.
repopulating it with proper data and trying to bring it back up doesn’t work and it still comes up with IPV6 address somehow.